Email Alert For Stock Less

Hi all,
Please help me on how to get email alert for admin when stock less than 3.
The admin will get automaticly email notification in his mailbox.
Anyone who know about this?

Thank you.

If we are talking about an ecommerce site:

On the payment confirmed page that the customer sees when completing payment successfully, you could email the admin if the stock level has dropped below three.
If there is a 'shipped' status for orders, you could instead perform the same check and email at that point.

Another option would be to have a daily cron job run that calls a PHP script. That script could generate a report on any items that are low in stock that you could then email to the admin.